Permanent completion of wells



Dec. 26, 1961 R JR 3,014,533

PERMANENT COMPLETION OF WELLS Filed Sept. 22, 1958 /3 H. Moore, z/r.

INVENTOR.

ATTORNEY 3,914,533 Patented Dec. 26, 1961 This invention relates topermanent completion Well installations and more particularly to theplacement in a well hole and the embedment in a hole-filling solidcement column of conductor equipment through which all of the variousworking and reworking operations and the usual production of well fluidsare accomplished.

In conventional well practices-and after a hole has been drilled throughthe earth from a surface location and to a production zone, the wall ofthe bored hole is lined throughout its depth by a large diameter hollowtubular casing. Thereafter a production conduit or string of tubingsections of smaller diameter is lowered through the casing in concentricrelation thereto and usually a packer is set between the two strings forclosing off the annular space from the production zone for well fluidflow through the inner string to the surface. A well liner casing andits enclosed annular space serve many useful purposes and, among otherthings, permit the production tubing string to be withdrawn for theperformance of reworking operations. I

As distinguished from past procedures, it is here proposed to install aWell tubing assembly which has all the advantages of but does not employthe customary large diameter casing and which assembly, once installed,remains in place and yet permits all of the necessary working operationsto be readily performed. Forcertain well conditions, considerablesavings are effected not only in the simplification of maintenance andreworking operations but also in the original cost for the drilling of awell hole, inasmuch as a much smaller well hole can be bored, and onewhich is only slightly larger than the tubing string is entirelyfeasible and is desirable inasmuch as the work of bringing in a Well andthe time required are considerably lessened, and since the tubingassembly is permanently cemented within the hole, at least for aconsiderable portion of its bottom length and on occasion throughoutsubstantially its entire length, it follows that the smaller the hole,the less will be the volume of cement required to bridge the bore spacesurrounding the tubing string.

Reference is to be made to the accompanying drawing wherein FIG. 1 is amore or less diagrammatic illustration in exaggerated proportions of aWell installation in verti cal section according to the presentimprovement; FIG. 2 is an enlarged vertical section'of a parallel stringmandrel having a side pocket in one of the string passages for removablyreceiving a retrievable tool for effecting control of a communicatingopening between the mandrel passages; and FIG. 3 is a transverse sectionon line 3--3 of FIG. 2.

In FIG. 1 the conduit assembly of parallel tubing strings/ll and 2extends in radially spaced relation with the wall 3 of a well holedrilled from the earths surface 4 to intersect a subterranean oil, gasor other well fluid production zone 5. Each tubing string consists of alarge number of end to end connected pipe sections inelusive of severalspecially formed mandrels 6 common to both strings and located atpreselected vertically spaced apart intervals. 7

Each mandrel 6, as shown in FIGS. 2 and 3, contains a pair of side byside vertical passages, one of which is afforded by a hollow or tubularpipe section 7 whose opposite ends are externally screw threaded foraligned coupling connection within and as a part of the tubing string ormacaroni line pipe 1. The bottom of the tubular section 7, forming apart of the lowermost of a group of installed mandrels and whichordinarily will be within the production zone 5, as seen in FIG. 1, willbe plugged or capped as a lower terminal of the tubing string 1 and thistubing string constitutes a passageway which can be utilized forpurposes for which the conventional casing annulus space is oftenemployed. The other tubing string 2 extends further downwardly a shortdistance below the lowermost mandrel d for eventual receptionof theconventional cement plug and float collar and constitutes a wellproduction tubing conductor. Where the two strings rise above the groundsurface 4, they will be provided with suitable control valving, aslshownat 8 and 9 in the respective tubing strings l and 2.

All of the production string tubing sections, inclusive of the passagesthrough the several mandrels 6, are coaxial and are of approximately thesame internal diameter for a full-open bore on a straight line andthrough which wire line tools may be passed. That hollow portion of eachmandrel 6 within which is formed a straight through full-open productionpassage Ill has terminal internally threaded tubular extensions 11 forcoupling with adjoining production string sections. Between thesecoupling terminals ll the mandrel wall is enlarged and oifset to oneside from the tubing axis and conveniently is of oblong outline intransverse section to enclose a side pocket or chamber laterallydisplaced from the full-open straight through passage in. Welded orotherwise fixed within the lower portion of the offset pocket is a tube12- open at opposite ends and affording a receiver for removablylocating any selected one of a number of conventional Well tools loweredto or retrieved therefrom by the well known wire line equipment passagedthrough the straight through open bore string 2. The chamber space abovethe offset receiver 12 aifords working clearance for the manipulation ofthe wireline equipment in a manner well understood in the art.

Intermediate the open ends of the tubular receiver 12 there is formed anannular internal groove 13 and an intersecting radial port 14 in thewall of the receiver for communication with a lateral port 15 in thewall of the mandrel tube 7 and by way of a port connecting tube or sideextension passage 16 whose opposite ends are sealed and welded to thetubes 7 and 18. Additional weldments join abutting walls of the mandreltube 7 and mandrel housing 6 for securing the parts in unitary assembly.Above and below the internal groove 13, the interior surfaces of thereceiver 12 are accurately machined and finished smooth for a closesealing fit to such packings as may be carried by any retrievable toolpositioned therein.

By way of example, one such tool is shown .at 17 in FIG. '2 and may beconsidered. as an ordinary gas lift valve which controls the passage ofpressure gas from the conwhich block communication, can similarly bereceived at each mandrel and in any desired combination for theperformance of a given job. When no such tool is fitted to the offsetreceiver, the two parallel tubing string passages in the mandrel commonto both strings are in free communication with one another through theports 14 and 15 and the vertically spaced apart open ends of thereceiver l2. 7

Because the retrievable tool receivers are laterally offset from theproduction passages It}, a full-open and straight line bore ismaintained for the'whole length of the well and tools can be installedin and removed from any mandrel selectively. Furthermore, with thestring intercommunicating controls offset from interference, otherconventional tools may be located within the fullopen bore of theproduction string 2 according to known practices. By way ofillustration, there is shown a conventional landing nipple 18incorporated in the tubing string 2 just above the mandrel 6 next abovethe production zone 5, and such nipple, for example, can mount aremovable choke or the like. Such nipple can also be employed forsuspending a downwardly projecting extension tube of smaller diameterthan the production string, to co-operate therewith in providing aninternal passage and an external passage as upward and downward fiowpaths below the next to the lowermost mandrel as may enable circulationor pump-down in one string and exhaust in the other, as, for example, inperformance of cementing and washing operations. For centralizing theconductor assembly dur-- ing its installation, use is made of one ormore sets of the usual spring centralizers, as shown at 19.

For closing the upper end of the well hole, there is employed the knowncasing head and hanger equipment generally indicated at 2- at the upperend of a short length of easing tubing 21 which preferably is employedto extend through a surface layer and at least the weathered stratum ofthe earth. According to the'drawing, a solid cement column 22 extendsinto and overlaps the bottom of the surface casing 21 and otherwisecompletely fills the Well hole and embeds the parallel tubing string andmandrel assembly. After the cement, introduced as a slurry within theopen bore hole, has set, it is perforated in the usual manner, as shownat 23, into the production zone 5 and from within the production string2 by means of conventional perforating equipment lowered from thesurface. The long column of cement 22 seals the face of the uncased borewall and permanently encases therein the conductor assembly. In bulk,the cement required is kept fairly small by drilling a slim hole to adiameter only slightly greater than the maximum diameter of the doublestring and mandrel assembly. Thus an open hole of approximately sixinches across can be fitted with a production conduit of two inches, aparallel line pipe of about one and a quarter inches and connectingmandrels having a maximum transverse dimension of about five inches foran annular working clearance of about one-half inch, which is ample foraccommodating installation.

When the tubing assembly is to be set in a previously bored hole, thetubing sections are made up in the usual fashion at the surface andlowered through the bore in increments as succeeding sections arecoupled in end to end succession. Usually, before each mandrel is addedto the string, the communication opening between the two passages 7 and10 is closed off by the insertion of a blanking plug within the receiver12. Also, at spaced apart intervals, the parallel string sections arepreferably tied or banded together, as shown at 24, for keeping theparallel strings in proper assembly. After the complete string has beenlowered, it is ready to be cemented in place. The cement slurry sentdown through the conductor tube 2, is forced out at the bottom and risesin the drilled hole back up toward the top of the hole to the desiredlevel. Performance of the cementing operation through the tubing stringemploys the usual equipment, such as a fioat collar and a pump-downplug, shown above the guide shoe in FIG. 1, at the bottom of the tubingstring. For washing operations, such as the removal of cement fromwithin the bottom of the production string following a cementing job,the string intercommunicating passage at the lowermost mandrel can beopened for circulation of liquid directed downwardly in one of thetubing strings and returned to the surface in the other tubing string.By properly controlling communication between the tubing strings and atdifferent levels selectively, various operations can be taken care of asdesired. In addition to enabling the well to produce by itself or bymeans of either mechanical pumping apparatus or gas lift equipment,there can be readily performed all of the other conventional procedures,including melting of paraflin by circulating hot oil, the injection ofchemicals and the like, all without need for erecting a large workingrig. Communication between the strings can be established selectively atdifferent levels, either by removal of the initially installed blankingplugs in the mandrel receivers 12 or by the substitution of flow controlunits, and every necessary well job can be easily handled with equipmenton a wire line service truck.

What is claimed is:

In a permanently completed gas lift well installation, a productionstring of end to end connected tubing sections projected through a wellhole between the surface and a production zone, a plurality ofretrievable tool receiving mandrels incorporated in the string assections thereof at vertically spaced apart intervals and provided withfullopen passageways in axial alignment with the passageways through theother tubing sections, each such mandrel having a side chamber offsetlaterally from the full-open passageway therethrough and provided with achamber side wall opening, a lift gas delivery macaroni line pipeextending from the surface in parallel side by side relation with theproduction string and having passageway means communicating in parallelflow relationship with the side wall openings of all of said chambersand being otherwise closed at subsurface levels, lift gas supply meansconnected with the pipe line at the surface level thereof, a toollocating receiver in each offset chamber for retrievably positioning atool in flow control relation with the chamber side wall opening, aseries of wire line tools to be passaged through the tubing string andto be selectively and retrievably positioned in the receivers of saidmandrels and held thereby in flow control relationship with said sidewall openings and a column of cement filling the annular well hole spacearound said tubing string and said line pipe and said column of cementand the production string having intercornmunicating flow perforationstherethrough at and in communication with the production zone.

References Cited in the file of this patent UNITED STATES PATENTS171,563 Hardison Dec. 28, 1875 2,605,637 Rhoades Aug. 5, 1952 2,749,989Huber June 12, 1956 2,781,098 Bielstein Feb. 12, 1957 2,785,753 Spearow-Mar. 19, 1957 2,785,754 True Mar. 19, 1957 2,847,072 Lebourg Aug. 12,1958 2,923,357 Daflin Feb. 2, 1960

